from sys import stdin, stdout


def main():
    line = stdin.readline()
    parts = line.split()
    a = int(parts[0])
    rta = "No"
    if a >= 30:
        rta = "Yes"

    stdout.write(rta)


main() from sys import stdin, stdout def main():
    line = stdin.readline()
    parts = line.split()
    a = int(parts[0])
    rta = "No"
    if a >= 30:
        rta = "Yes"

    stdout.write(rta) main line = stdin.readline() line stdin.readline() stdin.readline stdin readline parts = line.split() parts line.split() line.split line split a = int(parts[0]) a int(parts[0]) int parts[0] parts 0 rta = "No" rta "No" if a >= 30:
        rta = "Yes"

     a >= 30 a 30 rta = "Yes" rta "Yes" stdout.write(rta) stdout.write stdout write rta main() main def main():
    line = stdin.readline()
    parts = line.split()
    a = int(parts[0])
    rta = "No"
    if a >= 30:
        rta = "Yes"

    stdout.write(rta) def main():
    line = stdin.readline()
    parts = line.split()
    a = int(parts[0])
    rta = "No"
    if a >= 30:
        rta = "Yes"

    stdout.write(rta) main
from sys import stdin, stdout


def main():
    line = stdin.readline()
    parts = line.split()
    a = int(parts[0])
    rta = "No"
    if a >= 30:
        rta = "Yes"

    stdout.write(rta)


main()